Electromigration in eutectic solder interconnects was studied at 120C, for up to 324h, using current stresses of 104A/cm2. Hillocks were observed at the anode, and voids at the cathode. The predominant diffusing species was Pb; as confirmed by its accumulation at the anode. Diffusion markers were used to measure the electromigration flux, and to calculate the effective charge for atomic diffusion.

Electromigration of Eutectic SnPb Solder Interconnects for Flip Chip Technology. T.Y.Lee, K.N.Tu, S.M.Kuo, D.R.Frear: Journal of Applied Physics, 2001, 89[6], 3189-94